Trans-2-(alkoxycarbonylethyl)lactams and trans-2-(carboxyethyl)lactams are intermediates in the synthesis of 1-(4-fluorophenyl)-3(R)-3(S)-hydroxy-3-(4-fluorophenyl)-propyl)!-4(S)-(4- hydroxyphenyl)-2-azetidinone, a cholesterol lowering agent disclosed in U.S. Pat. No. 5,767,115.
U.S. Pat. No. 5,618,707 discloses stereoselective microbial reduction of a keto intermediate (4-(4-fluoro-benzoyl)butyric acid or a phenyloxazolidinone conjugate thereof) to the corresponding hydroxy intermediate used in the preparation of the azetidinone. Preferred microorganisms used in the process are Zygosaccharomyces bailii or Schizosaccharomyces octosporus.